size = int(input("请输入棋盘大小："))
for i in range(size):
    for j in range(size):
        if i == 0 and j == 0:
            print("┏",end=' ' )
        elif i == 0 and j == size - 1:  
            print("┓",end=' ' )
        elif i ==size-1 and j == 0:
            print("┗",end=' ' )
        elif i ==size -1 and j == size - 1:
            print("┛",end='')
        elif j == 0:
            print("┠" ,end='')
        elif i == size - 1:
            print("┷" ,end='')   
        elif j == size - 1:   
            print("┨" ,end='')
        elif i == 0:
            print("┯" ,end='')    
        else:
            print("┼" ,end='')

    print('')







